I would say that after looking over his stats from last year and knowing that he will be splitting carries his year with 2 or 3 other people. (I say 3 thinking that either Hendrix or Golson will start and we see more read options.)
I would say a huge season would be breaking 1000yds again this season while scoring double digit TDs, but more importantly I see him becoming a go to player that this offence needs now without Mike. I want to see him with the ball on 3rd and short, not dance, and just hit the hole hard and pick up the tough first down late in the game.
In conclusion a huge season in my opinion would be over 1000 yards, 10+TDs, and a real leader and go to player in the offence that could really use a very stable and successful running game.